1. Field of the Invention
The present invention relates generally to the art of folding or reducing vertical supports, and more particularly to the art of walking aids that are capable of being reduced in size. More specifically, the present invention relates to an orthopedic crutch that can be reduced to one third of the operational length of such a walking aid.
2. Description of the Related Art
Many types and forms of vertical supports have been developed in the related areas of the art of the present invention. Poles, rods, canes and crutches have all been designed in ways that allow them to be reduced in size. However, there are several shortcomings in both the production and operation aspects of these inventions that would be desirable to cure.
U.S. Pat. No. 3,635,233 issued Jan. 18, 1972 to Robertson, shows a folding cane or crutch. A tension cord is attached to the top and bottom tubular segments and runs through any intermediate segments. The joints between segments are formed by male and female fittings integral to the tubular segments. Robertson describes very narrowly the structure of the male/female fittings and emphasizes that they are to be integral to the tubular segments. The cane in Robertson is adjusted to a limited extent for height by changing the position of the hand grip as seen in FIG. 6. Because the device in Robertson is a single vertical support, there is no provision for minimizing or accomodating the torque exerted on the support.
The two U.S. Pat. Nos. to Hyman, No. 3,730,544 issued May 1, 1973 and Re. No. 28,067 issued July 9, 1974, show collapsible ski pole and rod structures. Hyman uses male/female type fittings generally similar to Robertson. A flexible tether cord runs the length of the pole. Mechanical cocking and locking means are provided for applying tension to the cord, thus locking the tubular segments into a linear configuration. Due to the nature of the devices shown in Hyman's two patents, naturally there is no way to adjust the vertical height of either device. Like Robertson, the Hyman patents do not disclose any means for minimizing torsional forces.
U.S. Pat. No. 3,655,297 issued to Bolen, Jr. et al. on Apr. 11, 1972 discloses a coupling or joint for folding tubular parts--here, parts of a paddle. A single directional, hinged plug is anchored into one tube. The other end is slidably located in the second tube. Mounted at this second end is a screw threaded at both ends and narrower between the threadings. A nut is anchored inside the second tube. To secure the two tubes together, one pushes the plug into the second tube and screws the adjacent threading into the internal nut until the device is secure. Again, no means are shown for dealing with the torsional forces created when the device's supporting means is twisted.
A spring-loaded folding cane is shown in U.S. Pat. No. 4,527,579 issued to Knotter et al. on July 9, 1985. A relatively elaborate hinging joint is locked by the operator when a spring-loaded locking ring 33 is slipped over the axially aligned joint segments. To unlock the device in Knotter, the user pulls the locking ring up along the device's shaft against the biasing of the spring, and then, while holding the ring clear of the joint, folds the shaft. Once again, the problem of torsional forces is not addressed due to the nature of the device.
U.S. Pat. No. 3,886,962 issued to Diamontis on June 3, 1975 shows a collapsible crutch using a telescoping hinged joint and a relatively complex series of holes, buttons and slots. A pair of identical latch buttons are moved along slots on the two tubular elements of the crutch to release the hinges, allowing the crutch to be folded. A mechanically specific structure is used to accomplish locking. Diamontis provides for adjustability by making the arm rest 5 adjustable by means of locking buttons 8. Diamontis specifically states that the crutch user needs another person to assist in adjusting the height using the disclosed structure since two lock buttons must be maintained in a depressed position while the arm rest is pulled out.
Finally, two U.S. Pat. Nos. 4,253,478 to Husa issued Mar. 3, 1981 and 4,437,480 issued Mar. 20, 1984, show a folding crutch. A hinged plug is anchored to the lower tube of the crutch, while being slidable within the upper tube. To secure the two tubular segments, one pushes the plug up into the upper segment until a button locks the joint. The later Husa patent adds reinforcing rings outside the joint. Husa does not disclose any means for adjusting the height of the crutch nor dealing with torquing of the lower, single tube element.
Of the above patents, only Diamontis shows a collapsible crutch having more than one collapsible tubular member. All others show only a unitary folding or collapsing vertical support. Diamontis requires a pair of two-part locking mechanisms to assist the user in folding the crutch when not in use and also requires two people to adjust the operational height. Several of the other patents disclose aids that a user can fold without assistance, but, they sacrifice the added stability of having more than one vertical support. A two support walking aid that could be both adjustable and reducible by the user alone would therefore be a significant advancement in the art of reducible walking aids.